Mayhem: The bus hit a block of flats on Ladbroke Grove (Jeremy Selwyn)

Matt Kyprianou, 29, club manager at Anytime Fitness on Ladbroke Grove, told the Standard he saw the woman dive for cover before she was struck by the bus.

He said: “I heard a bang so I looked outside the window and watched as the bus hit a white Audi after it tried to swerve out of the way.

Scene: police put a cordon at the scene (Jeremy Selwyn)

“It mounted the pavement outside Kensal House and collided with a pedestrian who tried to jump out of the way but was crushed between the bus and a wall.

“I could the lady pinned underneath the bus as people were getting off screaming and crying with that somebody had been hit.

“It was chaos, the woman was trapped and I thought there was no way she was going to survive.

Scene: witnesses rush to check on the welfare of the woman (Richard Horwell)

"Fire engines lifted the bus up and she was talking to paramedics.

“Once she was released she was being worked on and to my amazement she was still alive. They then placed her in the ambulance.

Bus crash in Ladbroke Grove

“Loads of passengers were being treated for injuries at the scene.”

Justin Samuels, who works in a furniture shop opposite the scene of the crash, said bus passengers on the upper deck were thrown forward by the impact of the crash.

Vibrated: residents said their homes "shook like an earthquake" (Richard Horwell)

He said: "Two cars crashed and the bus swerved to avoid an Audi that span with the impact.

"There was a huge bang when it hit the wall, you could hear the passengers screaming.

"The lady must have been crossing when she got trapped under the bus."

Personal trainer Karim Roundi, 25, who lives opposite where the crash took place said he was on a lunch break when he witnessed the collision.

Scene: Emergency services have been called to Ladbroke Grove (@themanatlarge67 )

He told the Standard: “Someone stepped out onto a pedestrian crossing and a car slammed on its brakes.

“The car behind went into the back of it and the bus swerved out of the way to avoid colliding into them.

“It lost control and went up onto the pavement and hit a block of flats.

“I didn’t realise it hit a woman until I saw her arm underneath the bus.

The bus hit the woman on Ladbroke Grove

“The top window was smashed so I think people on the top deck must have been hurt as well, you could see them getting off the bus.

“There was a lot of screaming when it happened. I went to Sainsbury’s and came back to see police had locked off the road.”

Richard Horwell, whose flat overlooks Ladbroke Grove, said his building "shook like an earthquake" following the crash.

He added: "I thought a bomb had gone off so I ran to the window and just heard people screaming.

"People were crying on the street."

Scrambled: A London Air Ambulance was called to the scene, landing in a nearby park (Ali Nabi Nur)

Police, fire crews and ambulances were sent to the scene while a London Air Ambulance was also scrambled, landing in Emslie Horniman Pleasance, a park close to the scene.

Scotland Yard said no arrests had been made.

A London Ambulance Service spokeswoman said: "We were called at 11.51am today to reports of a road traffic collision at Ladbroke Grove.

“We sent multiple resources to the scene, including four ambulance crews, a single responder in a car, an incident response officer and our Hazardous Area Response Team. We also dispatched London’s Air Ambulance .

“The first of our medics arrived at the scene in under six minutes. We are treating a number of patients."

Transport for London said the crash is being investigated.

A spokesman said: “Just before midday today, a route 52 double deck bus, operated by Metroline, was involved in a collision with a pedestrian at the junction of Ladbroke Grove and Canal Way. Emergency services attended the scene.